Lyme disease : the cause, the cure, the controversy
by Barbour, Alan G., M.D
Vaccines
When sources of an infectious disease are unavoidable and when treatment is either nonexistent or only partially effective, we look to that cornerstone of preventive medicine: a vaccine. Malaria is an example. This parasite infection can be prevented by measures that interrupt at one step or another the disease’s transmission by mosquitoes. But now many vectors are resistant to the insecticides that once kept their numbers low. Malaria has been successfully treated with medicines such as quinine. But the malaria parasites themselves are becoming resistant to the effects of these treatments. As the standbys of prevention and treatment reveal vulnerabilities over time, there is keener interest in developing a vaccine to prevent malaria.
P1: Lyme disease,开发疫苗是个有争议的事情。但是疫苗的副作用不清楚,并且由于这种病rarely fatal (这里注意!JJ是非常FATAL,实际说的是不致命!!!意思反了,后面有题,不理解会选错的!)所以一点点可能的导致患者对副作用tolerance 低;同时,做好的疫苗不见的买的出去(这里没解释原因),举了另一个疫苗rocky mountain feverdisease的例子,某某就是最后那种疫苗卖不出去就停产了(有题问举例作用)
Although malaria’s global scope dwarfs that of Lyme disease, there are parallels between the two diseases which are instructive with respect to vaccines. For many years a vaccine for use in humans was generally thought of as a low-priority item for Lyme disease prevention, and in fact, some experts continue to dispute the proposition that a Lyme disease vaccine is needed. Tick bites were viewed as being avoidable by means of a few simple precautions for outdoor activities. Moreover, the disease was seen by most physicians as easily treated with antibiotics. There was, in addition, little apparent incentive for a company to develop and market a vaccine against the disease. A vaccine for the more frequently fatal tick-borne disease Rocky Mountain spotted fever was taken off the market for the lack of use. Inasmuch as Lyme disease is rarely fatal, the public’s acceptance of side effects or actual illness from a vaccine would be expected to be low. What with the amount of litigation against vaccines for proven killers such as whooping cough and diphtheria, how great would be the “bottom line” for a vaccine against a more benign infection? How tolerant, it was further asked, would people be of untoward reactions to a vaccine against an infection that could easily be avoided to begin with, and that could be treated if acquired?
These are discouraging considerations and doubts. Nevertheless, public and professional demand have grown to the point that efforts to develop a vaccine for humans are now under way on both sides of the Atlantic. One justification is the recognition, over the last decade, that the impact of Lyme disease on the health and quality of life in high-risk areas is considerable. In some communities 10 percent of the population have been infected. There has been only limited success to date in controlling the disease by interrupting transmission to people in these areas. For many suburban residents, exposure to infection is almost impossible to avoid. This is especially true for outdoor workers and residents of communities with many deer and infected ticks around homes. Although many early infections with B. burgdorferi come to a physician’s attention, further experience has shown that infections occur without the rash of erythema migrans having been noticed. In the rash’s absence it is difficult to distinguish Lyme disease from a summer virus infection. In these cases the infection may go untreated during the stage in which treatment is most effective.
People with late infection, like those with the early form of the disease, usually respond to antibiotic therapy, but longer treatments are required. Moreover, some patients with Lyme disease involving the joints or nervous system do not substantially improve even after intravenous antibiotics. The arthritis continues for months to years, or the fatigue and achiness persist long after the antibiotics have been discontinued. Notwithstanding doubts about the accuracy of some diagnoses of chronic Lyme disease, the specter of a large number of persons with unrelieved disabilities has been another factor in the increased interest in a Lyme disease vaccine.
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